<script>
    Person.prototype.say = function() {
        console.log('Hello');
    }
    Person.prototype.age = 18
function Person() {
    this.name = '田总'
}
let p = new Person();  // 实例对象
let p2 = new Person();
p.name = '田田'
p.say()
p2.say()
</script>